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MSK > 22 - Wrist Flexor Forearm > Flashcards

22 - Wrist Flexor Forearm Flashcards

1
Q

What do I need to know?

A
  1. Bones of forearm and relation to wrist and elbow. Radio-ulnar joint and pronation/supination
  2. Compartments
  3. Flexor/pronator insertions, nerve supply, actions
  4. Wrist bones
  5. Disposition of the radial, median and ulnar nerves
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2
Q

What are the only intrinsic movements of the forearm?

A

Pronation and supination i.e. rotatory movements where the radius is moved in an arc medially around the ulna

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3
Q

During pronation/supination the radio-ulnar joints act as … while the interosseous membrane acts as a …

A

Pivots

Hinge

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4
Q

The hand can be rotated almost … degrees around the long axis of the limb

A

360 degrees

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5
Q

How are the forearm compartments formed?

A

MIS and LIS and interosseous membrane. The compartments are . not symmetrically arranged until the distal forearm

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6
Q

What muscles control the rotatory movements of the forearm?

A

Pronator Teres
Pronator Quadratus
Supinator

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7
Q

Describe the difference in cross section at the distal and proximal forearm

A

Distal: 4 compartments due to arm ext/flex tendons inserting. Sup/Pro compartments come in laterally/medially/obliquely
Proximal: Symmetrical posterior/supinator and anterior/pronator compartments
(EXCEPT anterior has 2x mass and 3x strength

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8
Q

Which bone is broader at superior radio-ulnar joint?

A

ULNA - radial head is smaller. Distally the radius is broad and ulna head is small. Are the same triangle shape midway

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9
Q

What is the fibrous articular disc attached to and what is its function?

A

> Attached to medial radius and houses the head of the ulna by connecting to the ulnar styloid process. Separates the inferior radio-ulnar joint from the true wrist joint. Means the ulna does NOT articulate in the wrist joint (DOES at elbow joint)
strengthens the joint

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10
Q

Purpose of the ulnar and radial styloid processes?

A

Bony spikes for ligaments to attach to

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11
Q

Ulnar Notch?

A

Houses the round small lateral head of the ulna

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12
Q

What does the fibrous articular disc attach to?

A

Medial radius > ulnar styloid process

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13
Q

What structures and joints allow pronation to occur?

A
  • the proximal radius is held in place by the annular ligament while the distal radius rotates over the ulna at the inferior radio-ulnar joint permitted by the fibrous articular disc.
  • hand articulates with RADIUS so takes it with it during pronation
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14
Q

Where would you find a sacciform recess at the wrist?

A

At the inferior radio-ulnar joint NOT the wrist joint. Above the fibrous articular disc

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15
Q

What is the carrying angle?

A

Angle of the forearm from the arm at elbow joint. Stops arms hitting hips while walking. Bigger than 15 degrees in females as have bigger hips, smaller than 15 in males as they have bigger chest

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16
Q

What are the 3 functions of the interosseous membrane?

A
  1. Flexible hinge during pronation/supination
  2. Muscle attachment
  3. Force transmission
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17
Q

How does the interosseous aid in force transmission?

A

If a force is applied to the wrist then the radius only is put under tension so all the force would be transduced and concentrated to the small head of the radius at the elbow. The membrane transmisses/dilutes the force to the broader ended ulna at the elbow. It resists compressive forces

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18
Q

How many carpal bones are there

A

8 in two rows of 4

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19
Q

How many joints are there at the wrist?

A

3
> Radio-carpal
> Mid-carpal
> Carpo-metacarpal

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20
Q

Radio-carpal joint?

A

Between radius and fibrous articular disc, and the distal row of carpal bones (Scaphoid, Lunate, Triquetral, not really Pisiform as is too medial/on top of triquetral)
> flexion/extension, abduction/adduction and SOME rotation

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21
Q

Mid-carpal joint?

A

> Between the 2 rows of carpals

> Some flexion/extension

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22
Q

Carpo-metacarpal joint?

A

VERY little movement EXCEPT at the thumb which is very mobile
> between carpals and metacarpa;s

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23
Q

Where does the flexor retinaculum span from and what does it form?

A

The most lateral > medial carpal bones (Scaphoid and Trapezium to Pisiform and Hamate)
> forms a concave Carpal Tunnel through which the tendons of the flexor muscles (except PL) enter

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24
Q

What bone is most likely to fracture at the wrist/radio-carpal joint?

A

Scaphoid as articulates with the radius the most

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25
Q

What does the flexor retinaculum prevent?

A

Bowstringing (bulge away) and holds tendons against the wrist to provide a mechanical advantage

26
Q

How many Interphalangeal joints are there?

A

2 (proximal and distal) in fingers 1 in thumb

27
Q

What is the palmar aponeurosis?

A

A triangular fibrous sheet fanning out from the distal flexor retinaculum

28
Q

What tendon inserts into the palmar aponeurosis?

A

Palmaris longus after crossing over the flexor retinaculum

29
Q

What muscles originate from the medial epicondyle?

A
  • common flexor tendon

- NOT Pronator Teres, part of FDP, FPL has an ulnar origin

30
Q

Superficial muscles?

A

4 - 1 = 3

  • PT
  • FCR
  • PL
  • FCU
31
Q

Intermediate Muscle?

A

FDS

32
Q

Deep muscles?

A
  • FDP
  • FPL
  • PQ
33
Q

Where does the Median Nerve run?

A

Runs through the cubital fossa and then runs between the 2 heads of pronator teres

34
Q

Pronator Teres?

A

O: Medial supracondylar ridge
I: Superior lateral ulna
> pronates
> median nerve

35
Q

Flexor Carpi Radialis?

A

O: Common flexor tendon
I: Base of the 2nd Metacarpal
> flex wrist
> median n

36
Q

Palmaris Longus

A

O: Common Flexor Tendon
I: Palmar Aponeurosis to each finger (anchors skin of the palm as experiences a lot of shear forces)
> runs OVER flexor retinaculum and through the common synovial sheath of the palm
> 30% don’t have and weakly flexes wrist and interphalangeal joints
> Median n

37
Q

Flexor Carpi Ulnaris

A

O: Common Flexor Tendon
I: Pisiform which is attached to the base of the 5th metatarsal
> ULNAR n
> flexes wrist

38
Q

Flexor Digitorum Superficialis

A 
O:
> Radial head
> Humero-ulnar head
I: Split tendon inserts at the base of the MIDDLE phalynx of the digits
> Median
> can only flex PROXIMAL IP joint
39
Q

Flexor Digitorum Profundus?

A

O: Anterior Ulna and Interosseous Membrane
I: Base of Distal Phalynx
> flexes distal IP joint (claw hand)
> half Median and Half Ulnar n

40
Q

Flexor Pollicis Longus

A 
O: Inferior half of ulna and inter oss
I: Base of distal phalynx of thumb
> flexing the thumb opposes the other fingers so needs own flexors
> Median N
> flex thumb
41
Q

Hand has a … arterial supply

A

Dual

42
Q

Pronator Quadratus?

A

Distal ulna > radius
> median n
> pronates
> is also an active stabiliser to keep the 2 bones together at their distal ends

43
Q

Describe the course of the median nerve

A
  • runs medial to biceps
  • dives into cubital fossa beneath bicipital aponeurosis
  • heads laterally through the 2 heads of PT
  • gives of the Anterior Interosseous Nerve as it runs deep along the inteross memb
  • median nerve continues in hand to give off palmar cutaneous nerve and RECURRENT branch
  • terminates as proper palmar digital nerves
44
Q

What does the median nerve and its branches supply?

A 
Median: Superficial and intermediate
> PT, FCR, PL, FDS
Anterior Interosseous Nerve: Deep
> FDP (half), FPL, PQ
Palmar Cutaneous Branch
Recurrent Branch
> Lateral 2 lumbricals and Thenar Muscles
Proper Palmar Digital Nerves
45
Q

Does the Median Nerve run under or over the retinaculum?

A

UNDER

46
Q

Describe the course of the Ulnar Nerve

A
  • runs medially with median n and brachial artery until it runs posterior to MIS and medial epicondyle
  • returns anteriorly between the heads of FCU
  • gives off palmar cutaneous n
  • gives off DORSAL cutaneous branch
  • runs OVER the flexor retinaculum
  • continues as deep branch ulnar nerve to supply most of the hand muscles
47
Q

FDS acts as the … for the nerves and arteries

A

ROOF (ulnar nerve runs under this after passing between heads of FCU)

48
Q

What does the ulnar nerve and its branches supply?

A 
Ulnar: 1/2 FDP and FCU
Palmar Cutaneous
DORSAL Cutaneous Branch
Deep Branch Ulnar
> most intrinsic muscles of the hand
Proper Palmar Digital Nerves
49
Q

Where does the anterior interosseous nerve branch off and where do the interosseous arteries branch off?

A

Median Nerve

Ulnar Artery

50
Q

Describe the course of the forearm arteries

A

> brachial artery divides in cubital fosaa to ulnar and radial
radial artery continues unbranched to wrist where it divides into deep/superficial branches
ulnar artery (may) divides into common interosseous artery and then continues into wrist to divide deep/superificial
CIA divides into anterior and posterior interosseous arteries. The anterior one runs with the ant inteross nerve from the MEDIAN nerve
the 2 interosseous arteries anastomose at the posterior distal forearm once anterior passes through a hole in membrane

51
Q

What artery may be used for a bypass in the arm?

A

Radial artery - hand has dual supply and this artery has no/little branching. Only IF ulnar gives a good enough supply

52
Q

The … artery acts as a boundary in the forearm. How?

A

Radial artery - anything medial to this artery is part of the flexor/pronator compartment and anything lateral is part of the extensor/supinator compartment

53
Q

What artery is more important?

A

Ulnar

54
Q

Which of the 2 interossei arteries is bigger?

A

The anterior due to ant comp having more muscle mass. Even sends perforating branches through to the posterior.

55
Q

Most lateral structure at the carpal tunnel?

A

Radial Artery

56
Q

Most medial structure at the carpal tunnel?

A

FCU

57
Q

Carpal tunnel tendons, vessels and nerves lateral to medial

A 
Radial Artery
FCR
FPL
Median Nerve
PL (NOT under ret)
FDS
FDP
Ulnar Artery 
Ulnar Nerve
FCU
58
Q

Nerves or arteries more lateral at carpal tunnel?

A

Arteries

59
Q

What arteries and nerves go THROUGH the carpal tunnel and which don’t?

A

Median Nerve does. NO arteries do (ulnar or radial). Ulnar nerve does NOT

60
Q

What tendons does the median nerve run beside?

A

FDP medially and palmaris longus laterally

61
Q

What MC are FDS and FDP in line with?

A

3rd metacarpal

MSK (29 decks)

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